Lead acidic cells are used in a wide range of applications such as in electric vehicles, vehicles, solar systems, inverters and uninterrupted power supplies. If curing of the lead acidic cell is not done properly during the manufacturing process of lead acidic cell then, the negative terminal of the cell starts shedding. Further, due to overcharging or undercharging of the lead acidic cell, the plate of the lead acidic cell also starts shedding. Conventionally, lead acidic cell use hazardous chemicals such as concentrated sulphuric acid and lead. The concentrated sulphuric acid generates fumes of sulphur dioxide that can be even fatal. Further, the lead used in the lead acidic cell can emit particles which may result in lead poisoning.
In the prior art packs sometimes, electronic circuits are used alongwith the cells. U.S. Pat. No. 8,384,360 discloses a hybrid battery pack which includes a converter, a controller, an ultracapacitor and a battery. The pack disclosed in the U.S. Pat. No. 8,384,360 is configured for use in a vehicle. As suggested in the U.S. Pat. No. 8,384,360, an ultracapacitor supplies current to crank a vehicle. The ultracapacitor required for cranking the vehicle has a capacitance greater than a 1000 Farads. Such an ultracapacitor required for cranking a vehicle is relatively expensive, prone to failure and also prone to a relatively high self discharge. The ultracapcitor suggested by the U.S. Pat. No. 8,384,360 for starting/cranking a vehicle does not provide sustained power. The power source suggested in the U.S. Pat. No. 8,384,360 is a conventional lead acidic battery or VRLA. These batteries suffer from the same drawbacks as pointed out for lead acidic cells.
Therefore, there is felt a need for a hybrid power pack which:
provides a high discharge current;
protects the environment from the fumes of sulphur dioxide and particles emitted by lead; provides sustained DC power;
is able to start/crank a vehicle without using a capacitor having a relatively high capacitance; and
limits deep discharge.